An in situ combustion process for recovering heavy oil using scaled physical model

In order to study the effects of formation thickness and structural dip on in situ combustion and the combustion performance in the 1/4 of inverted nine-spot injection pattern, the scaled experimental system was developed based upon the ISC scaling law. The laboratory results show that within 1/4 of inverted nine-spot injection pattern the main combustion zone was swept completely with the oil recovery of 75%, leaving 5–15% oil saturation in the cracking/vaporization zone. Gas override and early breakthrough became more and more serious when the formation thickness increased, and oil recovery in the reservoir with structural dip was much lower than that in the 0° structural dip reservoir under same operating conditions. Conclusions have been drawn that employing nine inverted nine-spot injection pattern ISC can achieve a good oil recovery in G3-6-18 reservoir of Liaohe Oilfield in China. However, the formation thickness and the structural dip shall be taken into account when a project is designed as they play a major role on the sweeping efficiency. The sweeping efficiency can be enhanced by optimizing the operational parameters.